As T-Mobile continues to shake up the wireless industry, AT&T is showing signs of stress — based on its latest earnings report.

AT&T on Tuesday reported fiscal fourth quarterprofit of $6.9 billion with earnings of $1.31 per share, compared to a $39 billion loss, or 68 cents a share, on the year ago quarter (statement). Non-GAAP earnings were 53 cents on revenue of $33.2 billion, up nearly 2 percent year-over-year.

Wall Street was expecting earnings of 50 cents per share on revenue of $33.06 billion for the quarter.

AT&T may have beaten analyst expectations but T-Mobile's efforts to ruffle feathers in the wireless industry are showing on AT&T's balance sheet — not least because AT&T scored just 566,000 net wireless postpaid adds during the quarter.

While AT&T also provides wireline, voice and managed IT services, 56 percent of the company's revenue comes from wireless and cellular. But T-Mobile has taken every opportunity over the past year to dig its claws as far as it can into the second largest U.S. carrier.

In 2013 alone, T-Mobile introduced a streamlined plan structure for new customers dubbed "Uncarrier," which all but killed off contracts and phone subsidies. Then, upping the ante, the introduction of the "Simple Choice" plan allowed customers unlimited international data roaming plans — something the wireless industry had been dining out on for years as a prime money-maker on business and international customers.

And AT&T's latest results shows that the stresslines are showing as a result of T-Mobile's moves.

Image: AT&amp;T Investors

AT&T chairman and chief executive Randall Stephenson said in prepared comments that the company will continue to make its networks "even more powerful" and "layer on services" to drive new growth.

He added: "We have good momentum in areas like connected car, home automation and mobile business solutions. We're also committed to transforming our operations to make them more responsive and efficient. To that end, we've launched Project Agile, a broad set of initiatives to streamline and improve every part of our business. Execution has begun and will be a focus area for us in 2014 and beyond."